Merge with mastersetuptools-scm

1 files changed, 28 insertions, 8 deletions

diff --git a/setuptools/command/build_ext.py b/setuptools/command/build_ext.py
index 1caf8c81..454c91fb 100644
--- a/setuptools/command/build_ext.py
+++ b/setuptools/command/build_ext.py
@@ -1,14 +1,16 @@
+import os
+import sys
+import itertools
+import imp
 from distutils.command.build_ext import build_ext as _du_build_ext
 from distutils.file_util import copy_file
 from distutils.ccompiler import new_compiler
-from distutils.sysconfig import customize_compiler
+from distutils.sysconfig import customize_compiler, get_config_var
 from distutils.errors import DistutilsError
 from distutils import log
-import os
-import sys
-import itertools
 
 from setuptools.extension import Library
+from setuptools.extern import six
 
 try:
     # Attempt to use Cython for building extensions, if available
@@ -16,10 +18,8 @@ try:
 except ImportError:
     _build_ext = _du_build_ext
 
-from distutils.sysconfig import get_config_var
-
-get_config_var("LDSHARED")  # make sure _config_vars is initialized
-del get_config_var
+# make sure _config_vars is initialized
+get_config_var("LDSHARED")
 from distutils.sysconfig import _config_vars as _CONFIG_VARS
 
 
@@ -59,7 +59,18 @@ elif os.name != 'nt':
 
 if_dl = lambda s: s if have_rtld else ''
 
+
+def get_abi3_suffix():
+    """Return the file extension for an abi3-compliant Extension()"""
+    for suffix, _, _ in (s for s in imp.get_suffixes() if s[2] == imp.C_EXTENSION):
+        if '.abi3' in suffix:   # Unix
+            return suffix
+        elif suffix == '.pyd':  # Windows
+            return suffix
+
+
 class build_ext(_build_ext):
+
     def run(self):
         """Build extensions in build directory, then copy if --inplace"""
         old_inplace, self.inplace = self.inplace, 0
@@ -94,6 +105,15 @@ class build_ext(_build_ext):
         filename = _build_ext.get_ext_filename(self, fullname)
         if fullname in self.ext_map:
             ext = self.ext_map[fullname]
+            use_abi3 = (
+                six.PY3
+                and getattr(ext, 'py_limited_api')
+                and get_abi3_suffix()
+            )
+            if use_abi3:
+                so_ext = get_config_var('EXT_SUFFIX')
+                filename = filename[:-len(so_ext)]
+                filename = filename + get_abi3_suffix()
             if isinstance(ext, Library):
                 fn, ext = os.path.splitext(filename)
                 return self.shlib_compiler.library_filename(fn, libtype)